I would think 100 ± 10 grains of either Triple7 or BH209 behind a Speer .451 Uni-Cor of 250-300 grains, a .452 XTP mag or non-mag of the same weight range, in either a Harvester Crushed Rib or Short Black (depending upon bullet length, short black for the lighter ones) or a Hornady 200 grain 10mm in MMP blue sabot would shoot just fine.

Mine has been accurate with everything I've put through it but my best group with the rifle to date has been with the 200 grain 10mm XTP load.